Allergies are very common worldwide and their prevalence is increasing. An allergic reaction is a hypersensitivity disorder of the immune system. The immune system normally protects the body from harmful agents such as bacteria and toxins. Its overreaction to an otherwise harmless substance is called an allergic reaction. The substance that causes a reaction is called allergen.
The severity of the reaction depends on the person's immune system response, and it could range from mild to severe.
For example, anaphylaxis is an acute multisystemic severe allergic reaction that is rapid on onset and may cause death. In fact, a fatal event has been reported to occur in 0.5-2% of cases of anaphylaxis. The most frequent triggers are food and drugs, followed by stings, latex, anisakis and other causes.
The only adequate treatment during an anaphylaxis is applying as soon as possible an injection of epinephrine (also known as adrenaline). Thus, patients who have anaphylactic reactions must carry auto-injectable doses of epinephrine always with them, as recommended in all the medical guidelines. The auto-injector or injector pen of epinephrine will allow them to apply the doses to themselves in case of anaphylaxis.
However, in practice this has many drawbacks:                The patient has to control the epinephrine, performing a periodic visual inspection (evaluating transparency) and controlling temperature, as the effectiveness of the epinephrine depends on the active ingredient being in good condition;        The patient might forget to carry the auto-injector or even deliberately not carry it because they might be ashamed and see it as a stigma as it discloses they have an illness;        The patient might be afraid of injecting the epinephrine, due to unfamiliarity with its use or fear of adverse events. In more serious reactions it could happen that the patient cannot self-inject the drug because he/she is unconscious;        The patient might forget or might not know how to use the auto-injector or injector pen.        
Consequently, there is a need for a system that at least partially solves the aforementioned problems.